Theory of pair production and radiation in inhomogeneous strong electromagnetic fields

本项目研究了非均匀强电磁场中相对论电子/粒子的辐射和γ射线对的产生，以及临界场下真空稳定性的有关问题。首先，我们发展了相对论离子自由束缚对产生理论。当相对论性离子沿晶体长轴沿着进入晶体时，离子感受到的晶体场相当于相干光子的周期性脉冲，可视为“虚拟X射线激光”。在离子的静止帧处，场强度可能变得超过临界场。在这种情况下，离子有可能在其束缚态产生一个电子：束缚态对的产生。这一过程不仅对强场QED理论的研究具有重要意义，而且对产生反氢或奇异原子的应用也具有重要意义。我们对产生的正电子末态用平面波，对产生的电子末态用相对论类氢态计算了这个过程，并与Muller等人的结果进行了比较。假设使用未来的X射线激光器，我们发现具有实际厚度的晶体给出比Muller等人的更大的对产生概率。其次，我们考虑了在相对论电子进入晶体轴向电场（10^ V/cm）的条件下，利用波包产生的诱导型对产生<12>。如果我们在电子静止坐标系中看到它，这种情况相当于Mein悖论。为了研究Klein佯谬型对的产生，我们用数值方法计算了波包的运动。作为基本的研究，我们用纳尔逊的随机力学计算了波包的运动。

In this project, we have studied radiation from relativistic electrons/pasitmns and pair production by gamma-rays in inhomogeneous strong electromagnetic fields and other problems related with the vacuum stability under the critical field.First, we have developed a theory of free-bound pair production by relativistic ions. It should be noted that when a relativistic ion enters a crystal along the major axis, the ion feels the crystal field that is equivalent to the periodic pulse of coherent photons which may be regarded as "virtual X-ray laser". At the rest frame of the ion the field strength may become beyond the critical field. In that case it is possible for the ion to produce an electron in its bound state: the bound-state pair production. This process is not only important for the investigating the strong-field QED theory but also for the application to producing antihydrogens or exotic atoms. We have calculated this process by using the plane wave for the final state of produced positron and the relativistic hydrogen like state for the final state of produced electron. By comparing our result with that of Muller, et al., which assume the use of a future X-ray laser, we have found that a crystal with realistic thickness gives larger pair production probability than that of Muller, et al..Second, we have considered the induced type of pair production by using a wave packet under the condition that a relativistic electron enters the crystal axial electric field (10^<12>V/cm). This situation is equivalent to the Mein paradox if we see it in the electron rest frame. We have numerically calculated the motion of the wave packet for the purpose of investigating the Klein paradox type pair production Also, as a fundamental investigation, we have calculated the motion of the wave packet by using Nelson's stochastic mechanics.